Regular Expressions 101

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An explanation of your regex will be automatically generated as you type.
Detailed match information will be displayed here automatically.
  • All Tokens
  • Common Tokens
  • General Tokens
  • Anchors
  • Meta Sequences
  • Quantifiers
  • Group Constructs
  • Character Classes
  • Flags/Modifiers
  • Substitution
  • A single character of: a, b or c
    [abc]
  • A single character of: a, b, c or d
    [[ab][cd]]
  • A character except: a, b or c
    [^abc]
  • A character in the range: a-z
    [a-z]
  • A character not in the range: a-z
    [^a-z]
  • A character in the range: a-z or A-Z
    [a-zA-Z]
  • Character class intersection
    [\w&&[^\d]]
  • Any single character
    .
  • Alternate - match either a or b
    a|b
  • Any whitespace character
    \s
  • Any non-whitespace character
    \S
  • Any digit
    \d
  • Any non-digit
    \D
  • Any word character
    \w
  • Any non-word character
    \W
  • Match everything enclosed
    (?:...)
  • Capture everything enclosed
    (...)
  • Zero or one of a
    a?
  • Zero or more of a
    a*
  • One or more of a
    a+
  • Exactly 3 of a
    a{3}
  • 3 or more of a
    a{3,}
  • Between 3 and 6 of a
    a{3,6}
  • Start of string
    ^
  • End of string
    $
  • A word boundary
    \b
  • Non-word boundary
    \B

Regular Expression
No Match

"
"
gm

Test String

Code Generator

Generated Code

import java.util.regex.Matcher; import java.util.regex.Pattern; public class Example { public static void main(String[] args) { final String regex = "^((?:[01][0-9]{0,2}|(?:2(?:5[0-5]{0,1}|[0-4][0-9]{0,1}|[6-9]{0,1}))|[3-9][0-9]{0,1})\\.){3}(?:[01][0-9]{0,2}|(?:2(?:5[0-5]{0,1}|[0-4][0-9]{0,1}|[6-9]{0,1}))|[3-9][0-9]{0,1})$"; final String string = "000.12.12.034\n" + "01.1.1.1\n" + "121.234.12.12\n" + "23.45.12.56\n" + "000.12.234.23.23\n" + "666.666.23.23\n" + ".213.123.23.32\n" + "23.45.22.32.\n" + "I.Am.not.an.ip\n" + "1.1.1.1\n" + "0.0.0.0\n" + "255.2.2.255\n" + "256.0.0.33\n" + "199.200.0.22\n" + "000\n" + "111\n" + "0\n" + "00\n" + "1\n" + "00\n" + "11\n" + "99\n" + "90\n" + "2\n" + "3\n" + "4\n" + "292\n" + "999\n" + "255\n" + "266\n" + "299\n" + "256\n" + "199\n" + "244\n\n" + "000.12.12.034\n" + "121.234.12.12\n" + "23.45.12.56\n" + "00.12.123.123123.123\n" + "122.23\n" + "Hello.IP\n\n"; final Pattern pattern = Pattern.compile(regex, Pattern.MULTILINE); final Matcher matcher = pattern.matcher(string); while (matcher.find()) { System.out.println("Full match: " + matcher.group(0)); for (int i = 1; i <= matcher.groupCount(); i++) { System.out.println("Group " + i + ": " + matcher.group(i)); } } } }

Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Java, please visit: https://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html